vulnerability / NVI-00003637 / Revision 2
Cross-site scripting (XSS) from writer field content in the site frontend
OSV carries this publisher advisory for getkirby/cms. This is an aggregated source copy; consult the original publisher and compare update dates.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
2.1 LOW (2.0)
nvd@nist.gov severity; no combined Null risk score.
7.3 HIGH (3.1)
security-advisories@github.com severity; no combined Null risk score.
5.4 MEDIUM (3.1)
nvd@nist.gov severity; no combined Null risk score.
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
getkirby/cms
source listedECOSYSTEM: introduced 3.5.0; fixed 3.5.8
### Impact Kirby's writer field stores its formatted content as HTML code. Unlike with other field types, it is not possible to escape HTML special characters against cross-site scripting (XSS) attacks, otherwise the formatting would be lost. Cross-site scripting (XSS) is a type of vulnerability that allows to execute any kind of JavaScript code inside the site frontend or Panel session of other users. If the user is logged in to the Panel, a harmful script can for example trigger requests to Kirby's API with the permissions of the victim. Because the writer field did not securely sanitize its contents on save, it was possible to inject malicious HTML code into the content file by sending it to Kirby's API directly without using the Panel. This malicious HTML code would then be displayed on the site frontend and executed in the browsers of site visitors and logged in users who are browsing the site. This vulnerability is critical if you might have potential attackers in your group of authenticated Panel users. They can escalate their privileges if they get access to
03 / Response
What to do next
- vendor patch
The original advisory lists fixed boundaries 3.5.8 for getkirby/cms. Confirm the publisher’s latest guidance.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database via OSV
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. NIST National Vulnerability Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-x7j7-qp7j-hw3q ↗
GitHub Advisory Database via OSV · vendor advisory
Observed . GitHub-origin advisory, CC-BY-4.0; OSV is an aggregate copy, not independent corroboration.
- CVE-2021-41252 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 2 ·
Source facts changed; compare the preserved prior revision.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.